The default disk space required for an OES 2 SP3 VM guest is 4 GB and the default allocation for each VM guest in Xen is 10 GB, leaving approximately 6 GB for data files, etc. The space you need is dependent on what you plan to use the virtual server for and what other virtual storage devices, such as NSS volumes, that you plan to attach to it.

10.1.2 Novell Storage Services Considerations

If you want to set up Novell Storage Services (NSS) on the virtual machine, note the following:

In a virtual environment, the devices that you want to use for the NSS file system on the guest operating system cannot exceed the 2 TB limit, even if the host operating system and guest operating system can handle larger devices.